Photographic compound



Patented Apr. 23, 1946 PHOTOGBAPHIC COMPOUND Woodrow Othell Wilson, LosAngeles, Calif., assignor to Wilson Lorraine Company, Los Angeles,Calif., a partnership composed of Woodrow Othell Wilson and Louis J.Platt No Drawing. Application February 1, 1944, Serial No. 520,695

2 Claims.

This invention relates to the art of photography and deals particularlywith a light sensitive substance suitable for making negatives, prints,and the like.

The invention to be described hereinafter has been developed primarilyfor use in the blueprint field, but as the description proceeds it willbecome evident to those skilled in the art that the above mentionedsubstance also referred to herein as a photographic compound will haveusefulness in any field where a light sensitive material may be used.

Th primary object of this invention is to pro- I vide a photographiccompound characterized by speed in response to light exposure,permanence in reproduction, ease of application for use, con-' venienceand economy in preparation, and inexpensive ingredients which go to makeup the compound. The light sensitive material to be disclosed herein hasbeen found in practice to have a very high light speed; that is, thetime of exposure of my compound is very short when compared with thetime required by the average blueprint compound used today. It has beenfound that, generally stated, the speed of exposure of my compound maybe in the neighborhood of forty-five seconds. Also, tests have been madewhich prove that reproductions made with my compound do not appreciablyfade over a period duce alight sensitive substance. As before stated.

the substance is highly sensitive to light and will yield upon exposurea gradation in intensity comparable to the exposure.

The compound comprises ferrous ammonium citrate. potassium ferricyanide,and potassium bichromaie. mixed in the following manner and in thefollowing proportions.

First: Dissolve one hundred grains of ferrous ammonium citrate in oneounce of distilled water.

Second: Dissolve fifty grains of potassium ferricyanide in one ounce ofdistilled water.

Third: Mix the two solutions together, forming two ounces of solution.

Fourth: Dissolve one grain of potassium bichromate in the solution fromthe above steps.

Fifth: Filter the solution and it is ready for use.

It is to be understood that the above amounts may be made more or lessas desired, the only limitation being that the proportions remain thesame; also, steps one and two may be reversed in order but step fourshould not be changed in its sequence.

The solution is applied as a light sensitive covering to papers. metalsurfaces, textiles, or any other substance desired by either spraying iton or painting it on with a suitable brush. Materials sensitized in thismanner may be exposed in the ordinary way and the-reproductionsdeveloped in a water bath. The color of the reproductions normally areblue, and various shades of blue may be obtained by regulating theexposures. the intensity of the color being directly proportional to theexposure. The reproductions are substantially permanent and may besubsequently treated in any well known manner for bleaching, or toobtain different colors, etc.

Having set forth my invention in general terms, what I claim as new andpatentable is:

1. A photographic compound consisting essentially of two parts offerrous ammonium citrate and one part of potassium ferricyanidedissolved in water with one fiftieth part of potassium bichromatedissolved therein.

2. The method of making a photographic compound consisting in mixing thefollowing ingredients in their following respective proportions: onehundred grains of ferrous ammonium citrate dissolved in one ounce oiwater, fifty (50) grains oi potassium ferricyanide dissolved in oneounce of water, combining the two solutions and dissolving therein one(1) grain of potassium bichromate.

WOODROW OTHEIL WILSON.

